diff --git a/src/tgbaalgos/minimize.cc b/src/tgbaalgos/minimize.cc
index 9d83a8e1d..f22a14ce1 100644
--- a/src/tgbaalgos/minimize.cc
+++ b/src/tgbaalgos/minimize.cc
@@ -638,6 +638,7 @@ namespace spot
     if (!f && !aut_neg_f)
       {
 	// We do not now if the minimization is safe.
+	delete min_aut_f;
 	return 0;
       }